Semiconductor packages are commonly used to house and protect integrated circuits, such as controllers, ASIC devices, sensors, etc. Semiconductor packaging should protect the integrated circuit from potentially damaging environmental conditions, such as extreme temperature variations, moisture, dust particles, etc. Packaging of sensor devices, such as MEMs (micro-electromechanical systems) sensor devices presents unique challenges. MEMs devices are commonly used to measure environmental parameters such as temperature, pressure, sound, composition of atmosphere, etc. The sensor elements require at least partial exposure to the exterior environment so that the environmental parameter can be measured, while the other circuits associated with the sensor elements should ideally be protected from the exterior environment. Accordingly, a MEMs package may include a roof or lid that protects the packaged items with an opening or port that exposes the MEMs sensor device to the exterior environment.
Particularly with regard to the packaging of acoustic MEMs devices (i.e., sensor devices having microphones), the performance of the MEMs device is highly dependent upon how well the microphone of the MEMs device can be positioned in the package structure. For example, in the case of a cavity-type package, larger background volumes of the interior cavity typically provide better performance. Further, for optimal performance, the MEMs device should ideally be placed as close to the port as possible.
Another design consideration in semiconductor packaging relates to the orientation of the package, relative to the article to which the package is connected (e.g., a global printed circuit board). In the case of MEMs applications, some users prefer the package to be mounted with the sound port facing downward towards the circuit board to which the package is electrically interfacing with. Other users prefer a reverse orientation of the sound port such that the MEMs device and port are opposite from the circuit board to which the package is electrically interfacing with.
One known package structure and associated technique for packaging MEMs devices involves the formation of PCB (printed circuit board) within the device package. The PCB allows for easy interconnection between the MEMs device and other devices contained within the package (e.g., ASIC devices). Further, two PCB layers can be provided in a single package to achieve a configuration in which the MEMs device and ASIC are on an opposite side of the package as the PCB layer in the package that is connected to the (global) circuit board to which the package is electrically interfacing with. This construction increases material costs and requires a high degree of precision during manufacturing. Although this can be avoided by only using one layer of PCB and mounting the MEMS device to this layer in either configuration, this option results in decreased performance for some configurations. Utilizing PCB within the package therefore suffers from the drawback of decreased compatibility and increased manufacturing costs.